<ul class='tags--topmenu'>

    {% url 'tags' as tags_url %}
    {% url 'tag_groups' as groups_url %}
    
    <li><a {% if request.get_full_path == tags_url %}class="active"{% endif %} href="{{tags_url}}">Tags</a></li>
    <li><a {% if request.get_full_path == groups_url %}class="active"{% endif %} href="{{groups_url}}">Tag Groups</a></li>
</ul>